Adult salmonid migration to natal habitats and spawning are affected both by physiological factors and environmental conditions. While research has focused on physiological thresholds that influence the initiation of migration, few studies have investigated the relationship between both hydrological and thermal conditions and salmon spawning throughout the course of the reproductive period. We examined whether Oregon coastal coho salmon (Oncorhynchus kisutch) returning to three tributaries of the Smith River watershed (in the central Oregon Coast Range) responded to the stream hydroregime throughout their spawning period. Generalised linear mixed models were constructed to evaluate relationships between various stream discharge metrics, water temperature and redd count data collected between 2010 and 2016. Across the three sub-basins we analysed, discharge and temperature metrics were important in explaining redd construction timing. However, the same parameters were not consistently important for every sub-basin. Water temperature was important in explaining redd construction in the largest sub-basin, North Sister Creek, and discharge metrics were consistently important in Beaver Creek, the smallest sub-basin. At the sub-basin scale, peak redd construction by coho salmon starts after increase in discharge (25th percentile) occurs but before the highest discharge events take place. However, synchrony among sub-basins was evident in delayed redd construction during 2013 when the autumn rains were delayed. Understanding relationships between the timing of redd construction and characteristics of the hydrological regime are critical to analysis of potential future climate impacts on all life stages of Oregon Coastal coho salmon.

中文翻译：

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俄勒冈州史密斯河水体系统与银鲑鱼 (Oncorhynchus kisutch) redd 结构的关系

成年鲑鱼迁移到出生栖息地和产卵受到生理因素和环境条件的影响。虽然研究的重点是影响迁移开始的生理阈值，但很少有研究调查水文和热条件与整个繁殖期鲑鱼产卵之间的关系。我们检查了俄勒冈州沿海银大麻哈鱼 ( Oncorhynchus kisutch) 返回史密斯河流域（位于俄勒冈海岸山脉中部）的三个支流在整个产卵期间对河流水体系统做出反应。构建了广义线性混合模型来评估 2010 年至 2016 年收集的各种河流流量指标、水温和 redd 计数数据之间的关系。在我们分析的三个子流域中，流量和温度指标对于解释 redd 施工时间很重要。然而，对于每个子流域，相同的参数并不总是很重要。水温对于解释最大的子流域 North Sister Creek 的 redd 构造很重要，而排放指标在最小的子流域 Beaver Creek 中一直很重要。在子流域尺度上，在排放量增加（第 25 个百分位数）发生之后，但在最高排放事件发生之前，银鲑鱼的峰值 redd 构建开始。然而，2013 年秋雨推迟时，子流域之间的同步性在延迟的redd 建设中很明显。了解 redd 构建时间与水文状况特征之间的关系对于分析未来气候对俄勒冈州沿海银鲑鱼所有生命阶段的潜在影响至关重要。